Functional Defects in Electroceramic Materials: Defect Design for Energy Storage Materials
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division
Program Organizers: Hui Xiong, Boise State University; Hua Zhou, Argonne National Laboratory; Yanhao Dong, Tsinghua University
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 9
Location: MS&T Virtual
Session Chair: Claire Xiong, Boise State University; Yanhao Dong, MIT
2:00 PM Invited
Design of Functional Decompositions for Solid State Batteries: Xin Li1; 1Harvard University
The energy density of battery system is limited largely by the electrochemical window of the electrolyte. In this talk, it is shown that how mechanically-induced metastability can greatly widen the operational voltage window of solid state batteries based on ceramic solid electrolyte far beyond organic liquid electrolytes. It is further shown both experimentally and theoretically that beyond the voltage window at high voltage how the decompositions of solid electrolyte in the bulk and at the interface to cathodes are modulated via the mechanical constraint, design of which forms a route toward higher voltage all-solid-state batteries. Our work is supported by a combination of high-throughput density functional theory simulations, machine learning analysis, advanced experimental characterizations and electrochemical solid-state battery tests.
2:30 PM Invited
Energetic Compromise for Achieving “Redox-Site-Rich” in Pseudocapacitive Energy Storage Materials: A Case Study of Nickel – aluminum Layered Double Hydroxides: Xianghui Zhang1; Cody Cockreham1; Su Ha1; Hongwu Xu2; Di Wu1; 1Washington State University; 2Los Alamos National Laboratory
Compositional modification by increasing concentration of redox site is effective to tune the energy density and enhance the performance of pseudocapacitive materials. Here, I report our recent study on the structure-energetics-performance relationships of nickel–aluminum layered double hydroxides (NiAl-LDHs) as a function of Ni/Al ratio. Specifically, increase of Ni/Al ratio results in expanded van der Waals gap, which leads to fast charge–discharge kinetics, degraded crystallinity, and high cycling stability. In addition, using acid solution calorimetry, in situ XRD, and in situ DRIFTS, we figure out that increase of Ni/Al ratio leads to energetically less stable as-made (hydrated) and dehydrated NiAl-LDHs, supported by experimentally measured formation enthalpies. Moreover, the highest specific capacity observed, 2128 F/g at 1 A/g, is owing to effective hydration that energetically stabilizes the Ni redox sites, solvates carbonate ions, and fills interlayer space, in other words, paying for the “energetic cost” of being “redox site rich”.
3:00 PM
Structure and Energetics of Point Defects in Titanium Dioxide: Shuyan Zhang1; Alan McGaughey1; Reeja Jayan1; 1Carnegie Mellon University
We apply molecular dynamics (MD) simulations to study the role of point defects, which can be induced during microwave radiation (MWR) assisted processing, on the structure of the rutile and anatase phases of titanium dioxide (TiO2). To probe defected TiO2 phases, a variable-charge force field is selected based on its transferability and its ability to predict material properties and defect formation energies. The lattice constant, elastic constants, and dielectric constants are predicted with good accuracy compared to experimental measurements. The mean square displacements of the ions are calculated for structures initialized with different concentrations of multiple types of point defect. The ionic translational mobility as the structures move toward equilibrium is enhanced as the defect concentration increases. Pair distribution function (PDF) analysis is applied to characterize the equilibrium structures and to allow for comparison to experimental measurements. Our findings provide insight into the formation and structure of defected TiO2 phases.
3:20 PM Invited
Formation of Two-dimensional Heterointerface in Layered Oxides for Improved Electrode Performance: Ekaterina Pomerantseva1; 1Drexel University
Synthetic strategies for the improvement in electronic conductivities and electrochemical stabilities of transition metal oxide cathodes are required for next-generation, high-performance battery systems. The chemical pre-intercalation approach, consisting of a sequence of a sol-gel process, extended aging, and a hydrothermal treatment, is a versatile synthesis technique that allows for the incorporation of polar species between the layers of transition metal oxides. Here, formation of a layered 2D δ-CxV2O5·nH2O heterostructure occurs via chemical pre-intercalation of dopamine molecules between bilayers of vanadium oxide followed by the hydrothermal treatment of the precipitate, leading to carbonization of the organic molecules. The improved electrochemical performance, in both extended cycling and rate capability experiments, of the 2D δ-CxV2O5·nH2O heterostructure electrodes in Li-ion cells is ascribed to the intermittent formation of carbon layers within the bilayered structure, which leads to increased electronic conductivity and improved structural stability of the heterostructure compared to the reference δ-V2O5·nH2O electrodes.
3:50 PM
Thermodynamic Insights into Engineering 2D Nano-ceramics Towards Powering Portable Electronic Devices: Cody Cockreham1; Xianghui Zhang1; Gengnan Li1; Hongwu Xu2; Di Wu1; 1Washington State University; 2Los Alamos National Laboratory
Two-dimensional (2D) nano-ceramic materials like transition metal-based layered double hydroxides (TM-LDH) and layered early transition metal carbides and nitrides (MXenes) are at the forefront of developing high-performance materials to meet the energy storage and power storage demands of portable electronics. Due to the presence of redox capable transition metals and large available surface areas, 2D nano-ceramics provide good specific capacitance and fast charge/discharge rates. These pseudocapacitive materials store charge with redox and intercalative active surface sites. To promote stable active surface sites we tune the chemistry, structure, and morphology. Manipulating the synthesis conditions of MXenes and TM-LDHs, we study the resulting relationships by investigating interlayer species, surface composition, structural/morphological order, and electrochemical performance. Using calorimetry, we probe the energetics of stability and surface interactions. By drawing connections with thermodynamic parameters to the synthesis-controlled variables of our engineered nano-ceramics, we provide insights to advance the design of functional ceramics.